Stable aqueous dispersions of biocides

ABSTRACT

An aqueous dispersion containing BIT and IPBC prepared using nonionic and anionic surfactants exhibits both chemical and physical stability and is suitable for use as a single product which is capable of imparting to a coating composition a high level of resistance against attack by a broad spectrum of organisms, including bacteria, fungi and algae, in both the wet-state and dry film-state.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application that claims priority of U.S.application Ser. No. 15/674,474, filed Aug. 10, 2017, entitled “STABLEAQUEOUS DISPERSIONS OF BIOCIDES”, which is a continuation of applicationSer. No. 15/234,621, filed Aug. 11, 2016 and now U.S. Pat. No. 9,756,859B1, all of which are hereby incorporated by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to stable aqueous dispersions of biocidesin relatively concentrated form which are useful for formulatingcompositions such as coating compositions that are resistant tomicrobiological attack in both the wet state and the dry film state.

DISCUSSION OF THE RELATED ART

The modern era of industrial biocides was ushered in by globalregulations banning the use of mercury- and other heavy metal-basedbiocides. This created an opportunity for the development of a largenumber of organic compound-based biocides that are safer to use.However, these new types of active ingredients have the disadvantagethat they are much more specific and limited in activity. Some areeffective against bacteria, some are effective as fungicides and stillothers are effective as algaecides. Even within each of these organismcategories, all of the known organic compound-based biocides have“gaps.” That is, they are more effective against certain species ofbacteria, fungi or algae than others. As a result, coatings producershave had to use a number of biocide products in order to achieveadequate protection of coating compositions against microbiologicalattack in both the wet state and the dry film state. At present,coatings producers need to separately purchase and formulate at leasttwo types of biocidal ingredients, a wet state preservative and a dryfilm preservative. While it has been recognized that in principle itshould be possible to combine wet state preservatives and dry filmpreservatives into a single biocide product having a broad spectrum ofactivity, the actual formulation of such a product has proven to bechallenging. This is because merely combining existing wet state and dryfilm biocide products results in numerous issues related to both thechemical and physical stability of such combined products. This isespecially true for attempts to combine existing BIT-containingwet-state preservative products with IPBC-containing dry-filmpreservatives. The alkalinity of the BIT preservatives degrades the IPBCover time, making it impractical to offer such combinations for salesince typically end users desire to be able to store biocide ingredientsfor extended periods prior to using the biocide ingredients in coatingcompositions and the like. Moreover, due to the water-insolubility ofmost biocides and the need to avoid the use of organic solvents, biocideproducts are generally sold in the form of aqueous dispersions havingrelatively high concentrations of biocide. It has proven to be quitedifficult to achieve long term physical stability in such concentratedbiocide dispersions, which exhibit a marked propensity to phase separateupon standing. This requires end users to take steps to re-homogenizeaqueous dispersions of biocides that have been stored for a period oftime, prior to withdrawing portions of such dispersions for use informulating coating compositions and the like.

Accordingly, there is a need for aqueous dispersions of biocides thatare both chemically and physically stable and that, as a single product,provide adequate protection of coating compositions against a wide rangeof microbiological hazards (i.e., a single product that when formulatedinto a coating composition simultaneously prevents or retardsmicrobiological growth both when the coating composition is in the wetstate as well as when it has been converted into a dry film).

SUMMARY OF THE INVENTION

The present invention provides a single biocide product, in the form ofa chemically and physically stable aqueous dispersion, that is capableof imparting a sufficient level of protection to a coating composition,both in the wet state and as a dry film, against a broad range oforganism types (algae, bacteria, fungi). Through the use of theinventive biocide compositions described herein, the need to formulate acoating composition using multiple sources of different biocides may beavoided. That is, adequate wet state and dry film state resistance tobiological attack of a coating composition may be attained using theinventive aqueous dispersion alone, without the addition of any otherbiocide-containing ingredient to the coating composition. At the sametime, the inventive aqueous dispersion is capable of being stored forextended periods of time at ambient temperatures without significantloss of physical homogeneity or breakdown of the biocide activeingredients.

An aqueous dispersion in accordance with the present invention thusprovides the following practical advantages, as compared to theconventional use in the coatings industry of separate wet-state anddry-film preservative packages:

i) Reduced cost to the end user (coatings formulator);

ii) Fewer different inventory items for the end user to purchase, storeand maintain;

iii) Operational simplicity, with only one biocide-containing product tobe metered into a coating composition rather than several; and

iv) Lessened environmental impact, due to the lower energy usage arisingfrom manufacturing, packaging and transporting a singlebiocide-containing product rather than several.

Various aspects of the invention may be summarized as follows:

Aspect 1: A composition useful for providing resistance tomicrobiological attack in both a wet state and a dry film state in asingle dose, wherein the composition is comprised of, consistsessentially of or consists of:

-   -   a) water;    -   b) 1% to 12% by weight 1,2-benzisothiazolin-3-one (BIT);    -   c) 2% to 50% by weight 3-iodo-2-propynyl butyl carbamate (IPBC),        wherein BIT and IPBC are present in amounts effective to provide        a weight ratio of BIT:IPBC of from 0.02 to 2;    -   d) at least one nonionic surfactant;    -   e) at least one anionic surfactant; and    -   f) at least one thickener/suspending agent, in an amount        effective to provide the composition with a viscosity of at        least 300 centipoise at 25° C.;        -   wherein d) and e) are present in an amount effective to            provide the composition in the form of a stable aqueous            dispersion.

Aspect 2: The composition of Aspect 1, comprising at least two differentnonionic surfactants.

Aspect 3: The composition of Aspect 1 or 2, comprising at least onealkoxylated aliphatic or aromatic mono-alcohol.

Aspect 4: The composition of any of Aspects 1-3, comprising at least twodifferent alkoxylated aliphatic mono-alcohols.

Aspect 5: The composition of any of Aspects 1-4, comprising a firstalkoxylated aliphatic mono-alcohol and a second alkoxylated aliphaticmono-alcohol each having an aliphatic mono-alcohol segment and analkoxylated segment, wherein the second alkoxylated aliphaticmono-alcohol differs from the first alkoxylated aliphatic mono-alcoholwith respect to at least one of a) chain length of the aliphaticmono-alcohol segment, b) composition of the alkoxylated segment, or c)number of oxyalkylene units in the alkoxylated segment.

Aspect 6: The composition of any of Aspects 1-5, comprising a firstalkoxylated aliphatic mono-alcohol which is an ethoxylated C10-C18aliphatic alcohol containing an average of about 6 to about 15 ethyleneoxide units per molecule and a second alkoxylated aliphatic mono-alcoholwhich is an alkoxylated C2-C8 aliphatic alcohol containing both ethyleneoxide and propylene oxide units.

Aspect 7: The composition of Aspect 6, wherein the first alkoxylatedaliphatic mono-alcohol is an ethoxylated C12-C16 linear aliphaticalcohol containing an average of about 8 to about 12 ethylene oxideunits per molecule.

Aspect 8: The composition of Aspect 6 or 7, wherein the secondalkoxylated aliphatic mono-alcohol is an alkoxylated n-butanolcontaining both ethylene oxide and propylene oxide units and having ablock copolymer structure.

Aspect 9: The composition of any of Aspects 1-8, wherein the at leastone anionic surfactant includes at least one sulfonate surfactant.

Aspect 10: The composition of any of Aspects 1-9, wherein the at leastone anionic surfactant includes at least one alkyl aryl sulfonate.

Aspect 11: The composition of any of Aspects 1-10, wherein the at leastone anionic surfactant includes at least one dodecyl benzene sulfonate.

Aspect 12: The composition of any of Aspects 1-11, wherein the at leastone thickener/suspending agent includes at least onethickener/suspending agent selected from the group consisting ofsilicates, polyacrylates, polysaccharides and clays.

Aspect 13: The composition of any of Aspects 1-12, wherein the weightratio of BIT:IPBC is from 0.5 to 1.8.

Aspect 14: The composition of any of Aspects 1-13, additionallycomprising at least one biocide selected from methylbenzimadazole-2-ylcarbamate and 3-(3,4-dichlorophenyl)-1,1-dimethylurea.

Aspect 15: The composition of any of Aspects 1-14, wherein thecomposition is comprised of from about 40 to about 60 weight % water.

Aspect 16: The composition of any of Aspects 1-15, wherein the at leastone nonionic surfactant and the at least one anionic surfactant arepresent in a weight ratio of nonionic surfactant:anionic surfactant offrom about 1.5:1 to about 8:1.

Aspect 17: The composition of any of Aspects 1-16, wherein biocides,including BIT and IPBC, the at least one nonionic surfactant and the atleast one anionic surfactant are present in a weight ratio ofbiocides:(nonionic surfactant+anionic surfactant) of from about 6:1 toabout 20:1.

Aspect 18: A composition useful for providing resistance tomicrobiological attack in both a wet state and a dry film state in asingle dose, wherein the composition is in the form of a stable aqueousdispersion and is comprised of, consists essentially of or consists of:

-   -   a) 45 to 60% by weight water    -   b) 3 to 9% by weight 1,2-benzisothiazolin-3-one (BIT);    -   c) 2 to 7% by weight 3-iodo-2-propynyl butyl carbamate (IPBC),        wherein BIT and IPBC are present in amounts effective to provide        a weight ratio of BIT:IPBC of from 0.5 to 1.8;    -   d) 5 to 20% by weight methylbenzimidazole-2-yl carbamate (BCM);    -   e) optionally, 3-(3,4-dichlorophenyl)-1,1-dimethylurea;    -   f) 0.5 to 3% by weight of at least two alkoxylated aliphatic        mono-alcohols, including a first alkoxylated aliphatic        mono-alcohol which is an ethoxylated C10-C18 aliphatic alcohol        containing an average of about 6 to about 15 ethylene oxide        units per molecule and a second alkoxylated aliphatic        mono-alcohol which is an alkoxylated C2-C8 aliphatic alcohol        containing both ethylene oxide and propylene oxide units;    -   g) 0.2 to 1% by weight of at least one sulfonate surfactant;    -   h) optionally, up to 1% by weight of at least one defoamer, and    -   i) at least one thickener/suspending agent, in an amount        effective to provide the composition with a viscosity of at        least 300 cps at 25° C.;        -   wherein the percentages by weight are based on the total            weight of a)-i).

Aspect 19: A coating composition which is resistant to microbiologicalattack in both a wet state and a dry film state, comprising acomposition in accordance with any of Aspects 1-18 and at least oneadditional coating ingredient.

Aspect 20: A method of making a coating composition which is resistantto microbiological attack in both a wet state and a dry film state,comprising combining one or more coating ingredients with an effectiveamount of the composition of any of Aspects 1-18 to obtain the coatingcomposition.

“Physically stable”, as used herein, means that the aqueous dispersionremains homogeneous and does not phase separate upon sitting for anextended period of time at normal storage conditions. For example, invarious embodiments of the invention, the aqueous dispersion may remainhomogeneous in appearance, as judged by a human observer, upon sitting(without agitation) at 40° C. for at least one week, at least two weeks,at least one month, at least two months, at least three months, at leastfour months, at least five months or even at least six months. In suchembodiments, the dispersed biocide particles may exhibit no visiblesettling out or flocculation over at least the stated periods of time.

“Chemically stable”, as used herein, means that the active ingredients(biocides) present in the aqueous dispersion do not chemically react ordegrade to a significant extent when the aqueous dispersion is storedfor an extended period of time under normal storage conditions. Forexample, in various embodiments of the invention, less than 10% or lessthan 5% loss of each of the biocides present in the aqueous dispersiontakes place upon storage at 40° C. in a sealed container for at leastone week, at least two weeks, at least one month, at least two months,at least three months, at least four months, at least five months oreven at least six months.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS OF THE INVENTION Water

Water is utilized in the aqueous dispersions of the present invention asa carrier or diluent for the other components of the aqueousdispersions, forming an aqueous phase within which fine particles of thebiocides are suspended in the form of an emulsion. Although one or moreorganic solvents may optionally be present in the aqueous dispersion inaddition to water, in particular water-miscible solvents such asalcohols, glycol ethers, esters and the like, it will generally bepreferred to minimize the amount of organic solvent or even to eliminateorganic solvent altogether. Thus, in various aspects of the invention,the aqueous dispersion contains less than 5%, less than 4%, less than3%, less than 2%, less than 1%, or less than 0.5% or even 0% by weight,based on the total weight of the aqueous dispersion, of organic solvent.The aqueous dispersion, in one embodiment, is VOC-free (i.e., free ofcompounds classified as “volatile organic compounds”).

Although the pH of the aqueous phase of the aqueous dispersion is notbelieved to be particularly critical, one or more pH adjusting agentsmay be included in the aqueous dispersion for the purpose of achieving adesired pH. The pH adjusting agents may be acidic or basic and may alsobe capable of functioning as buffers. In one aspect of the invention,the aqueous dispersion has a pH of from 3 to 10.

The amount of water may be varied as may be needed or desired in orderto provide an aqueous dispersion of suitable stability and biocideconcentration. Generally speaking, it will be desirable to minimize theamount of water present in order to provide an aqueous dispersion havingas high a concentration of biocides as can be attained while stillpreserving acceptable rheological properties and dispersion stability.In various embodiments of the invention, the water concentration in theaqueous dispersion may be at least 20%, at least 25%, at least 30%, atleast 35%, at least 40% or at least 45% by weight based on the totalweight of the aqueous dispersion, while in other embodiments the waterconcentration in the aqueous dispersion is not more than 80%, not morethan 75%, not more than 70%, not more than 65%, not more than 60%, notmore than 55%, not more than 50%, not more than 45% or not more than 40%by weight, based on the total weight of the aqueous dispersion. Incertain embodiments, the aqueous dispersion is comprised of from 40% to60% by weight water.

Biocides

The aqueous dispersions of the present invention contain at least twobiocides, namely, 1,2-benzisothiazol-3(2H)-one (CAS No. 2634-33-5, attimes referred to herein by the acronym “BIT”) and 3-iodoprop-2-yn-1-ylbutylcarbamate (CAS No. 55406-53-6, at times referred to herein by theacronym “IPBC”). Other commonly used names for BIT includebenzisothiazolinone, benzisothiazolin-3-one and benzisothiazolone. IPBCis sometimes alternatively referred to as 3-iodo-2-propynylN-butylcarbamate, 3-iodo-2-propynyl butyl carbamate or iodocarb. BIT ispresent in the aqueous dispersion in an amount of from 1% to 12% byweight, while IPBC is present in an amount of from 2% to 50% by weight.In various aspects of the invention, the aqueous dispersion contains 3%to 9% by weight of BIT and 2% to 40% by weight of IPBC. To provide asufficient degree of both wet state and dry film-state protection to acoating composition based on the aqueous dispersion against biologicalattack by bacteria, fungi, algae and other organisms, the weight ratioof BIT:IPBC should be controlled to be within the range of from 0.02 to2, limits included. In one aspect, the BIT:IPBC weight ratio is withinthe range of 0.5 to 1.8, limits included.

One or more other biocides may be present in the aqueous dispersioncompositions of the present invention, in addition to the BIT and theIPBC. In one aspect, the aqueous dispersion additionally comprisesmethylbenzimidazole-2-yl carbamate (“BCM”). The BCM content of theaqueous dispersion may be, for example, at least 1% by weight and/or notmore than 30% by weight, e.g., from 5% to 20% by weight. In a furtheraspect, the aqueous dispersion additionally comprises3-(3,4-dichlorphenyl)-1,1-dimethylurea (“Diuron”). The Diuron content ofthe aqueous dispersion may be, for example, at least 1% by weight and/ornot more than 25% by weight, e.g., from 10% to 20% by weight.

The aqueous dispersion may contain both BCM and Diuron, in addition toBIT and IPBC. In various aspects of the invention, the aqueousdispersion contains no biocide other than BIT, IPBC, BCM or Diuron or nomore than 10% by weight or no more than 5% by weight (based on the totalweight of biocide) of any biocide other than BIT, IPBC, BCM or Diuron.Thus, the aqueous dispersion may have a biocide component consisting ofor consisting essentially of BIT and IPBC and optionally one or both ofBCM and Diuron.

Other biocides which may be present in the aqueous dispersion include,but are limited to, any of the biocidal compounds known in the art.Supplemental wet-state actives that can be used include, but are notlimited to,5-chloro-2-methyl-2H-isothiazol-3-one/2-methyl-2H-isothiazol-3-one(“CMIT/MIT”) and 2-bromo-2-nitropropane-1,3-diol (“Bronopol”).Supplemental algaecides that can be used include, but are not limitedto, 2-tert-Butylamino-4-ethylamino-6-methylthio-1,3,5-triazin(“Terbutryn”) and 3-(4-isopropylphenyl)-1,1-dimethylurea(“Isoproturon”).

It will be advantageous for any biocide present in the aqueousdispersion to be in the form of relatively fine particles, for example,particles having a particle size of from 5 to 75 microns. The desiredparticle size may be attained through the use of conventional techniquessuch as grinding, milling, sieving and the like.

Surfactants

The aqueous dispersions of the present invention utilize a combinationof at least one nonionic surfactant and at least one anionic surfactant.In certain embodiments, the aqueous dispersion is characterized by theabsence of any type of surfactant other than nonionic and anionicsurfactants, such as cationic or amphoteric (zwitterionic) surfactants.The surfactants function as emulsifiers and help to keep thewater-insoluble components of the formulation in the form of a stabledispersion (emulsion) of small particles suspended in an aqueous phase.

In a preferred embodiment, the aqueous dispersion contains at least twodifferent nonionic surfactants. The nonionic surfactants may differ, forexample, with respect to the chemical structure (including chain length)of their hydrophobic segment(s), their hydrophilic segment(s), or boththeir hydrophobic segment(s) and their hydrophilic segment(s). Suitabletypes of nonionic surfactants include, but are not limited to,polyoxyalkylene glycol alkyl ethers (e.g., polyoxyethylene glycol alkylethers, polyoxypropylene alkyl ethers, polyoxyethylene/propylene alkylethers), glucoside alkyl ethers, polyoxyalkylene glycol alkylphenolethers (e.g., polyoxyethylene glycol alkylphenol ethers,polyoxypropylene glycol alkylphenol ethers, polyoxyethylene/propyleneglycol alkylphenol ethers), glycerol alkyl esters, polyoxyalkyleneglycol sorbitan alkyl esters (e.g., polyoxyethylene glycol sorbitanalkyl esters), sorbitan alkyl esters, cocamide MEA, cocamide DEA, blockcopolymers of polyethylene glycol and polypropylene glycol (poloxamers),polyalkoxylated tallow amines, alkoxylated fatty acids and the like andcombinations thereof.

Particularly advantageous nonionic surfactants include alkoxylatedaliphatic mono-alcohols and alkoxylated aromatic mono-alcohols. Suchsurfactants are typically prepared by reacting one or more alkyleneoxides (e.g., ethylene oxide, propylene oxide, mixtures of ethyleneoxide and propylene oxide) with one or more mono-alcohols (e.g.,aliphatic alcohols, which may be for example linear or branched, primaryor secondary, or aromatic alcohols, such as phenols, including alkyl-and aralkyl-substituted phenols). The number of moles of alkylene oxidereacted per mole of the mono-alcohol may be varied as may be desired,but typically is from about 2 to about 50 on average. If more than onetype of alkylene oxide is used, the alkylene oxides may be reacted as amixture (to provide a polyoxyalkylene segment having a random copolymerstructure) or sequentially (to provide a polyoxyalkylene segment havinga block copolymer structure).

One preferred type of nonionic surfactant for use in the presentinvention is an alkoxylated aliphatic mono-alcohol which is anethoxylated C10-C18 aliphatic alcohol (in particular, a linear primaryC12-C16 aliphatic alcohol (or mixture of such alcohols) which has beenreacted with about 6 to about 15 moles of ethylene oxide per mole ofaliphatic alcohol to provide an alkoxylated alcohol containing anaverage of about 6 to about 15 oxyethylene repeating units permolecule). For example, the alkoxylated aliphatic mono-alcohol may be anethoxylated C12-C16 linear aliphatic alcohol containing an average ofabout 8 to about 12 ethylene oxide units per molecule. In particular,ethoxylated tridecanol containing an average of about 10 ethylene oxideunits is suitable for use in the present invention.

Another preferred type of nonionic surfactant for use in the presentinvention is an alkoxylated C2-C8 aliphatic alcohol containing bothethylene oxide and propylene oxide units. The C2-C8 aliphatic alcoholmay be n-butanol, for example. The ethylene oxide and propylene unitsmay be arranged in a block manner (e.g., the surfactant may contain apolyoxyethylene block and a polyoxypropylene block).

Also suitable for use as nonionic surfactants are alkoxylated phenols,in particular ethoxylated phenols wherein the phenol may be substitutedwith one or more alkyl groups (in particular, long chain alkyl groupssuch as nonyl or dodecyl groups or aralkyl groups, such as intristyrylphenol).

Suitable anionic surfactants include, but are not limited to,surfactants containing anionic functional groups at their head, such assulfate groups, sulfonate groups, phosphate groups, and carboxylategroups. The cationic counterion to the anionic functional group may be,for example, an alkali metal (e.g., Na, K) or an amine (ammonium) cationsuch as a quaternary ammonium. Useful types of anionic surfactants whichmay be employed in the aqueous dispersions of the present inventioninclude, but are not limited to, alkyl sulfates, alkyl ether sulfates,sulfated alkanolamides, glyceride sulfates, alkyl aryl sulfonates(including straight-chain alkylbenzenesulfonates, branchedalkylbenzenesulfonates, alkylnaphthalenesulfonates), alpha olefinsulfonates, lignosulfonates, sulfo-carboxylic compounds (e.g., sodiumlauryl sulfoacetate, sulfosuccinates (including dialkylsulfosuccinates),sulfosuccinamates, organo phosphored surfactants, sacrosides,hydroxyalkanesulfonates, alkanesulfonates, alkylphenoxy polyoxyethylenepropyl sulfonates, salts of polyoxyethylene alkylsulfophenyl ethers,sodium N-methyl-N-oleyltaurates, monoamide disodiumN-alkylsulfosuccinates, petroleum sulfonates, sulfated castor oil,sulfated tallow oil, salts of sulfuric esters of aliphatic alkylesters,salts of alkyisulfuric esters, salts of alkylsulfuric esters, sulfuricesters of polyoxyethylenealkylethers, salts of sulfuric esters ofaliphatic monoglycerides, sodium salt of the monosulfated monoglycerideof hydrogenated coconut oil fatty acids, salts of sulfuric esters ofpolyoxyethylene alkylphenylethers, salts of alkylphosphoric esters,salts of phosphoric esters of polyoxyethylenealkylethers, salts ofphosphoric esters of polyoxyethylenealkylphenylethers, partiallysaponified compounds of styrene-maleic anhydride copolymers, partiallysaponified compounds of olefin-maleic anhydride copolymers,naphthalenesulfonate-formalin condensates, higher alkyl sulfoacetates,and higher fatty acid esters of 1,2-dihydroxy propane sulfonate andcombinations thereof. Particularly preferred among these anionicsurfactants are sulfonate surfactants, in particular salts of alkyl arylsulfonates, especially salts of C8-C18 alkyl benzene sulfonates such assalts of dodecylbenzene sulfonate, and combinations thereof.

A total amount of surfactant is utilized in the composition which iseffective, in combination with the thickener(s)/suspending agent(s) alsopresent in the composition, to provide a physically stable aqueousdispersion. The amount of surfactant needed to achieve a physicallystable dispersion will depend on a number of factors, including, forinstance, the types and amounts of biocides and thickeners/suspendingagents present and well as the types of surfactants utilized. Typically,however, an amount of surfactant is used which is sufficient to providea weight ratio of biocide:surfactant within the range of from about 5:1to about 50:1 or from about 6:1 to about 20:1.

Thickeners/Suspending Agents

The aqueous dispersions of the present invention additionally include atleast one substance capable of functioning as a thickener or suspendingagent such that, in cooperation with the surfactant component, theaqueous dispersion is rendered physically stable. In particular, thetype(s) and amount(s) of thickener/suspending agent are selected suchthat at 25° C. the resulting aqueous dispersion has a viscosity of atleast 300 cps. In other embodiments, the viscosity of the aqueousdispersion at 25° C. is at least 400 cps or at least 500 cps. Generallyspeaking, however, it will be desirable for the viscosity of the aqueousdispersion to not be increased to the point where it becomes difficultto transfer or handle the aqueous dispersion by means of pumping.Viscosity is measured using a Brookfield viscometer (spindle #5, 100rpm).

Suitable thickeners/suspending agents include, without limitation, clays(including natural clays and organo-modified clays), silicates (e.g.,silicas such as modified silicas and fumed silicas), polysaccharides(e.g., gums such as xanthan gum, cellulosic polymers), polyacrylates,and the like and combinations thereof.

Optional Additional Ingredients

One or more other components, in addition to those mentioned above, mayadditionally be present in the aqueous dispersions of the presentinvention. In certain embodiments, however, the aqueous dispersionconsists essentially of or consists of only the aforementionedcomponents, except that one or more defoamers may optionally be presentin such embodiments.

Optional additional components include, but are not limited to,defoamers (antifoams, e.g., silicone-based defoamers, mineral oil-baseddefoamers, hydrophobic silica-based defoamers), sequestering/chelatingagents, pH adjusting agents, fillers, coloring agents, antifreezingagents, corrosion inhibitors (anti-corrosion additives), ultravioletlight stabilizers, antioxidants, co-solvents, scale inhibitors,preservative, and the like.

Methods of Making

Aqueous dispersions in accordance with the present invention may beprepared by adaptation of any of the techniques known in the art forcreating dispersions of water-insoluble substances in water usingsurfactants (emulsifiers) and thickeners/suspending agents. For example,and as further illustrated by the working examples included herein, asuitably sized mixing vessel may be charged with water, followed by thesurfactants desired to be included in the aqueous dispersion. Whileagitating the surfactant/water mixture, the biocides and a portion ofthe thickeners/suspending agents are added. Mixing at high speed and/orhigh shear may be continued until a homogeneous emulsion having thedesired particle size (typically 5 to 75 microns) is obtained. Themixture may be heated to a temperature somewhat above room temperatureduring this step. The remaining thickeners/suspending agents may then beadded and the mixture agitated until homogeneous once again. The mixturemay be cooled to room temperature prior to the final addition ofthickeners/suspending agents. The aqueous dispersion may then betransferred by pumping or other means to one or more suitable storagecontainers such as tanks, drums or totes.

End Uses

Aqueous dispersions in accordance with the present invention are usefulfor imparting resistance to microorganism growth, including bacterial,fungal and algae growth, in a wide variety of products, in particularwater-based products. As the aqueous dispersions are typically preparedcontaining relatively high concentrations of active ingredients (i.e.,biocides), they generally find use as concentrates which are combined,in relatively small quantities, with one or more other ingredients inorder to formulate a final product suitable for use for its intendedpurpose (such as a coating composition, for example, wherein the otheringredients may include pigment(s), polymeric resin(s) (e.g., latexresins), a carrier vehicle such as water and so forth). In oneembodiment of the invention, the aqueous dispersion is dosed into acoating composition, in particular a water-based coating compositionsuch as a latex paint, in an amount representing from 0.2 to 2% byweight of the coating composition.

The aqueous dispersions of the present invention may, for instance, beemployed any of the following types of products: wood preservatives,paints, lazures, stains, plasters, EFIS (Exterior Finishing InsulationSystem, sometimes also referred to as Exterior Insulation FinishingSystem), mildewicides, adhesives, textiles, leather and hide treatment,non-woven fabrics, building materials, stucco, concrete, caulks,sealants, joint compounds, and any other application in which theinhibition or prevention of the growth of undesired microorganisms isdesired in both the wet-state and the dry-film state.

Within this specification, embodiments have been described in a waywhich enables a clear and concise specification to be written, but it isintended and will be appreciated that embodiments may be variouslycombined or separated without departing from the invention. For example,it will be appreciated that all preferred features described herein areapplicable to all aspects of the invention described herein.

In some embodiments, the invention herein can be construed as excludingany element or process step that does not materially affect the basicand novel characteristics of the composition or process. Additionally,in some embodiments, the invention can be construed as excluding anyelement or process step not specified herein.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

EXAMPLES Example 1

This Example demonstrates the preparation of a stable aqueous dispersionin accordance with the present invention which is suitable for use in aninterior paint product to provide simultaneous wet-state and dryfilm-state protection against biological attack.

To an appropriate size mixing vessel equipped with a high speed mixer,charge 51 parts water and start mixing at low speed. Charge thefollowing ingredients in succession: 0.6 parts by weight dodecylbenzenesulfonic acid isopropylamine salt, 0.4 parts by weight alkoxylatedalcohol surfactant A (ethoxylated tridecanol containing an average ofabout 10 ethylene oxide units per molecule), and 1 part by weightalkoxylated alcohol surfactant B (n-butanol alkoxylated with propyleneoxide and ethylene oxide in a block manner). While gradually increasingagitation as the mixture thickens, add the following ingredients: 7.2parts by weight 1,2-benzisothiazolin-3-one (BIT, 85%), 15 parts byweight methylbenzimdazole-2-yl carbamate (BCM, technical grade), 15.3parts by weight natural clay (thickener), 1 part by weight modifiedsilica (suspending agent), 5.4 parts by weight 3-iodo-2-propynyl butylcarbamate (IPBC), and 0.2 parts by weight defoamer. While maintaining atemperature at or below 40° C., mix at high speed until a homogeneousemulsion with a desired particle size, typically 5 to 75 microns, isreached. Cool to room temperature, then add 0.3 parts by weight xanthangum (thickener) and 0.4 parts by weight of a product containing 9.5% byweight BIT and 90.5% by weight inert ingredients. Stir for 30 minutesuntil homogeneous. The resulting creamy white emulsion was analyzed andfound to contain 4.5% by weight IPBC, 14.6% by weight BCM, and 6.4% byweight BIT and to have a viscosity at 25° C. of 642 cps. After holdingfor three months at 40° C., the creamy white emulsion was found tocontain 4.2% by weight IPBC, 14.3% by weight BCM, and 6.2% by weightBIT. The product obtained remained a homogeneous creamy white emulsionafter holding for three months at 40° C.

The ability of the product thus prepared to provide bacterial resistanceto a coating composition was demonstrated by stirring a portion of theaqueous dispersion of Example 1 into a standard acrylic paint containingno microbicide. A 50-gram aliquot of each sample was inoculated with 0.5mL of a mixed bacterial culture containing Alcatigenes faecalis (ATCC#25094), Enterobacter aerogenes (ATCC #13048), Escherichia coli (ATCC#11229), and Pseudomonas aeruginosa (ATCC #10145). The resulting aliquotwas streaked on Petri dishes of TGEA at intervals of 24 hours, 48 hours,and 7 days. To obtain a second week of data, the same samples werere-inoculated with the same mixed culture and retested. The Petri disheswere evaluated for extent of bacterial growth using a subjective scalefrom 0 to 4, where 0 is completely free of growth and 4 is completelyovergrown. The results obtained are shown in Table 1.

TABLE 1 Bacterial Resistance First Second Mildew Resistance InoculationInoculation A. niger A. pullans T. viride P. fellutanum 24 hr 48 hr 7days 24 hr 48 hr 7 da 4 wk 4 wk 4 wk 4 wk Blank 4 4 4 4 4 4 4 2 3 3 0.2%1 0 0 2 0 0 1 1 1 1 Example 1 0.3% 0 0 0 1 0 0 1 1 1 1 Example 1

Mildew resistance was demonstrated on the same spiked paint above. Thepaint was applied over Leneta charts and cured for 7 days. The squareswere placed on sterile 2% Malt Agar petri plates. Spore suspensions ofthe four fungal species were made from four-week-old cultures grown onMalt Agar. Each test organism was tested separately. One mL of anindividual fungal spore suspension was distributed over the surface ofeach sample. Duplicate plates of each sample were prepared. The petriplates containing the test samples were incubated for four weeks at 80°F. and 70% relative humidity. Each sample was evaluated for extent offungal growth at four weeks using a subjective scale from 1 to 4 where 1is completely free of growth and 4 is completely overgrown. Testorganisms were Aspergillus niger (ATCC #1015), Aureobasidium pullulans(ATCC #9348), Penicillin fellutamum (ATCC #10443), and Trichodermaviride (ATCC #20476). The ratings observed are shown in Table 1.

Example 2

This Example demonstrates the preparation of a stable aqueous dispersionin accordance with the present invention which is suitable for use in anexterior paint product to provide simultaneous wet-state and dryfilm-state protection against biological attack.

To an appropriate size mixing vessel equipped with a high speed mixer,charge 53.6 parts water and start mixing at low speed. Charge thefollowing ingredients in succession: 0.6 parts by weight dodecylbenzenesulfonic acid isopropylamine salt, 0.4 parts by weight alkoxylatedalcohol surfactant A (ethoxylated tridecanol containing an average ofabout 10 ethylene oxide units per molecule), 1 part by weightalkoxylated alcohol surfactant B (n-butanol alkoxylated with propyleneoxide and ethylene oxide in a block manner), and 2 parts by weightethoxylated tristyrylphenol (containing an average of about 16 molesethylene oxide per mole of tristyrylphenol). While gradually increasingagitation as the mixture thickens, add the following ingredients: 4.3parts by weight 1,2-benzisothialin-3-one (BIT, 85%), 15.5 parts byweight 3-(3,4-dichlorphenyl)-1,1-dimethylurea (Diuron), 9.3 parts byweight methylbenzimidazole-2-yl carbamate (BCM, technical grade), 10.2parts by weight natural clay (thickener), 1 part by weight modifiedsilica, 3.4 parts by weight 3-ido-2-propynyl butyl carbamate (IPBC), and0.6 parts by weight defoamer. While maintaining a temperature at orbelow 40°, mix at high speed for 2 hours or until a homogeneous emulsionwith a desired particle size, typically 5 to 75 microns, is reached.Cool to room temperature, then add 0.3 parts by weight xanthan gum(thickener) and 0.4 parts by weight of a product containing 9.5% byweight BIT and 90.5% by weight inert ingredients. Stir for 30 minutesuntil homogeneous. The resulting creamy white emulsion was analyzed andfound to contain 3.7% by weight IPBC, 9.1% by weight BCM, 6.5% by weightBIT, and 15.4% by weight Diuron and to have a viscosity at 25° C. of 642cps.

The product obtained remained a homogeneous creamy white emulsion afterholding for one month at 40° C. At this time, the creamy white emulsionwas found to contain 3.4% IPBC, 8.8% BCM, 3.4% BIT and 15.2% by weightDiuron.

The aqueous dispersion obtained was subjected to the same test protocolas described in Example 1. The results of the testing are shown in Table2. Since the aqueous dispersion additionally contained an algaecide, itwas also evaluated for algae resistance.

Algae resistance was demonstrated on the same spiked paint above. Onecoat of each sample was applied to both sides of Whatman #2 filter paperin duplicate and air dried for 72 hours. A 0.35 ml suspension of algaewas spread over the plate with a “Drigalski” spatula. Two 1 inch squareswere cut from each specimen and placed on Proteose agar plates.One-hundred (100) μl of algae suspension was placed on top of eachfilter paper square. The petri dishes were then incubated for two weeksat 15 degrees C., 52% RH and 4000-lux light. The samples were evaluatedfor extent of algae growth at four weeks using a subjective scale from 1to 4, where 1 is completely free of growth and 4 is completelyovergrown. Test Organisms were Chlorella vulgaris var viridis (ATCC#16487), Chlorellasp. (Troy isolate), and Stichococcus bacillaris (BIUC#K-150). Ratings are shown in Table 2.

TABLE 2 Algae Resistance Chlorella vulgaris varviridis + ChlorellaBacterial Resistance sp. + First Second Mildew Resistance StichococcusInoculation Inoculation A. niger A. pullans T. viride P. fellutanumbacillaris 24 hr 48 hr 7 da 24 hr 48 hr 7 da 4 Wk 4 Wk 4 Wk 4 Wk 4 WkBlank 4 4 4 4 4 4 4 2 3 3 2 0.2% 0 0 0 1 0 0 1 1 1 1 0 Example 2

The following examples (Examples 3 and 4) illustrate that it is notpossible to blend conventional BIT-containing wet-state solutions andcombine them with existing IPBC-containing dry-film products and obtaina chemically or physically stable biocidal product.

Example 3

To an appropriate size mixing vessel equipped with a high speed mixer,charge 2 parts by weight Polyphase® 678 (a water-based dispersion ofIPBC and BCM, sold by Troy Corporation) and 3 parts by weight Mergal®B10K (a ready-to-use solution containing 9.5% by weight BIT, sold byTroy Corporation). The resulting creamy white emulsion was analyzed andfound to contain 1.97% by weight IPBC, 5.9% by weight BCM and 6% byweight BIT. After holding at 3 months at 40° C., the mixture was againanalyzed and found to contain 0.55% IPBC, 6.2% BCM and 4.8% BIT (i.e.,significant loss of IPBC and BIT had occurred). Upon standing at roomtemperature for two weeks, the emulsion broke, forming two layers.

Example 4

To an appropriate size mixing vessel equipped with a high speed mixer,charge 2 parts by weight Polyphase® 663 (a water-based productcontaining 9% by weight BCM, 3% by weight IPBC and 15% by weightDiuron), and 3 parts by weight Mergal® B10K (a ready-to-use solutioncontaining 9.5% by weight BIT, sold by Troy Corporation). Upon standingat room temperature for two weeks, the emulsion broke to form twolayers.

The following examples (Examples 5-7) illustrate that it is not possibleto even blend BIT-containing wet-state dispersions (which avoids thealkalinity that destroys IPBC) and combine them with existingIPBC-containing dry-film products and obtain a physically stablebiocidal product.

Example 5

A mixture of 11.3 grams Mergal® 753 (an aqueous dispersion productcontaining 44.9% by weight BIT sold by Troy Corporation), 38 gramsPolyphase® 678 (a water-based dispersion of IPBC, sold by TroyCorporation), and 50.7 grams deionized water were added to a beaker andmechanically stirred for 15 minutes. When mechanical stirring stopped,the resulting milky white dispersion separated into two layers. Thisdemonstrates that even the simple blending of existing wet-state anddry-film dispersion products does not result in a physically stableproduct.

Example 6

A mixture of 10 grams Mergal® 753 (an aqueous dispersion productcontaining 44.9% by weight BIT sold by Troy Corporation), 67.4 gramsPolyphase® 678 (a water-based dispersion of IPBC, sold by TroyCorporation), and 20.6 grams deionized water were added to a beaker andmechanically stirred for 15 minutes. When mechanical stirring stopped,the resulting milky white dispersion separated into two layers

Example 7

A mixture of 11.3 grams Mergal® 753 (an aqueous dispersion productcontaining 44.9% by weight BIT sold by Troy Corporation), 38 gramsPolyphase® 663 (a water-based product containing 9% by weight BCM, 3% byweight IPBC and 15% by weight Diuron), and 50.7 grams deionized waterwere added to a beaker and mechanically stirred for 15 minutes. Whenmechanical stirring was stopped, the resulting milky white dispersionseparated into two layers.

Example 8

A stable aqueous dispersion in accordance with the present inventionwhich is suitable for use as a concentrate in the formulation of anexterior paint may be prepared using the procedures described inExamples 1 and 2 and the components listed in Table 2.

TABLE 2 Component Weight Percent Function Dodecylbenzene 0.6 Surfactant(Emulsifier) Sulfonic Acid Isopropylamine Salt Alkoxylated Alcohol 0.4Surfactant (Emulsifier) Surfactant A¹ Modified Silica 1Thickener/Suspending Agent Alkoxylated Alcohol 1 Surfactant (Emulsifier)Surfactant B² Polyacrylate 2 Thickener/Suspending Agent Natural Clay10.2 Thickener/Suspending Agent Diuron 15.5 Active Ingredient (Biocide)Xanthan Gum 0.3 Thickener/Suspending Agent Defoamer 0.6 DefoamerMergal ® K10N³ 0.4 Active Ingredient (Biocide) 1,2-Benzisothiazolin- 4.3Active Ingredient (Biocide) 3-one (BIT, 85%) Water 51 Diluent BCM 9.3Active Ingredient (Biocide) IPBC 3.4 Active Ingredient (Biocide)¹ethoxylated tridecanol containing an average of about 10 ethylene oxideunits per molecule²n-butanol alkoxylated with propylene oxide andethylene oxide in a block manner³a ready-to-use solution containing 9.5%by weight BIT, sold by Troy Corporation

Example 9

A stable aqueous dispersion in accordance with the present inventionwhich is suitable for use as a concentrate in the formulation of aninterior paint may be prepared using the procedures described inExamples 1 and 2 and the components listed in Table 3.

TABLE 3 Component Weight Percent Function Dodecylbenzene 0.6 Surfactant(Emulsifier) Sulfonic Acid Isopropylamine Salt Alkoxylated Alcohol 0.4Surfactant (Emulsifier) Surfactant A¹ Modified Silica 1Thickener/Suspending Agent Alkoxylated Alcohol 1 Surfactant (Emulsifier)Surfactant B² Natural Clay 15.3 Thickener/Suspending Agent Xanthan Gum0.3 Thickener/Suspending Agent Defoamer 0.2 Defoamer 1,2- 7.2 ActiveIngredient (Biocide) Benzisothiazolin-3- one (BIT, 85%) Water 53.6Diluent BCM 15 Active Ingredient (Biocide) IPBC 5.4 Active Ingredient(Biocide)

Example 10

A stable aqueous dispersion in accordance with the present applicationmay be prepared using the following procedure. To an appropriate sizemixing vessel equipped with a high speed mixer, charge 41.6 parts byweight water and start mixing at low speed. Charge 1 part by weight of anonionic alkoxylated alcohol surfactant which is n-butanol alkoxylatedwith propylene oxide and ethylene oxide in a block manner and 0.6 partby weight of an anionic surfactant which is the isopropyl amine salt ofdodecylbenzene sulfonate. While gradually increasing agitation as themixture thickens, add the following ingredients: 7.2 parts by weight BIT(85%), 0.5 part by weight fumed silica, 8.7 parts by weight natural clay(thickener), 40 parts by weight IPBC, 0.1 parts by weight defoamer, and0.3 parts xanthan gum (thickener). Stir for 30 minutes untilhomogeneous.

What is claimed is:
 1. A composition useful for providing resistance tomicrobiological attack in both a wet state and a dry film state in asingle dose, wherein the composition is comprised of: a) water; b) 1% to12% by weight 1,2-benzisothiazolin-3-one (BIT); c) 2% to 50% by weight3-iodo-2-propynl butyl carbamate (IPBC), wherein BIT and IPBC arepresent in amounts effective to provide a weight ratio of BIT:IPBC offrom 0.02 to 2; d) at least one nonionic surfactant; e) at least oneanionic surfactant; and f) at least one thickener/suspending agent, inan amount effective to provide the composition with a viscosity of atleast 300 centipoise at 25° C.; wherein d) and e) are present in anamount effective to provide the composition in the form of a stableaqueous dispersion.
 2. The composition of claim 1, comprising at leasttwo different nonionic surfactants.
 3. The composition of claim 1,comprising at least one alkoxylated aliphatic or aromatic mono-alcohol.4. The composition of claim 1, comprising at least two differentalkoxylated aliphatic mono-alcohols.
 5. The composition of claim 1,comprising a first alkoxylated aliphatic mono-alcohol and a secondalkoxylated aliphatic mono-alcohol each having an aliphatic mono-alcoholsegment and an alkoxylated segment, wherein the second alkoxylatedaliphatic mono-alcohol differs from the first alkoxylated aliphaticmono-alcohol with respect to at least one of a) chain length of thealiphatic mono-alcohol segment, b) composition of the alkoxylatedsegment, or c) number of oxyalkylene units in the alkoxylated segment.6. The composition of claim 1, comprising a first alkoxylated aliphaticmono-alcohol which is an ethoxylated C10-C18 aliphatic alcoholcontaining an average of about 6 to about 15 ethylene oxide units permolecule and a second alkoxylated aliphatic mono-alcohol which is analkoxylated C2-C8 aliphatic alcohol containing both ethylene oxide andpropylene oxide units.
 7. The composition of claim 6, wherein the firstalkoxylated aliphatic mono-alcohol which is an ethoxylated C12-C16linear aliphatic alcohol containing an average of about 8 to about 12ethylene oxide units per molecule.
 8. The composition of claim 6,wherein the second alkoxylated aliphatic mono-alcohol is an alkoxylatedn-butanol containing both ethylene oxide and propylene oxide units andhaving a block copolymer structure.
 9. The composition of claim 1,wherein the at least one anionic surfactant includes at least onesulfonate surfactant.
 10. The composition of claim 1, wherein the atleast one anionic surfactant includes at least one alkyl aryl sulfonate.11. The composition of claim 1, wherein the at least one anionicsurfactant includes at least one dodecyl benzene sulfonate.
 12. Thecomposition of claim 1, wherein the at least one thickener/suspendingagent includes at least one thickener/suspending agent selected from thegroup consisting of silicates, polyacrylates, polysaccharides and clays.13. The composition of claim 1, wherein the weight ratio of BIT:IPBC isfrom 0.5 to 1.8.
 14. The composition of claim 1, additionally comprisingat least one biocide selected from methylbenzimadazole-2-yl carbamateand 3-(3,4-dichlorophenyl)-1,1-dimethylurea.
 15. The composition ofclaim 1, wherein the composition is comprised of from about 40 to about60 weight % water.
 16. The composition of claim 1, wherein the at leastone nonionic surfactant and the at least one anionic surfactant arepresent in a weight ratio of nonionic surfactant:anionic surfactant offrom about 1.5:1 to about 8:1.
 17. The composition of claim 1, whereinbiocides, including BIT and IPBC, the at least one nonionic surfactantand the at least one anionic surfactant are present in a weight ratio ofbiocides:(nonionic surfactant+anionic surfactant) of from about 6:1 toabout 20:1.
 18. A composition useful for providing resistance tomicrobiological attack in both a wet state and a dry film state in asingle dose, wherein the composition is in the form of a stable aqueousdispersion and is comprised of: a) 45 to 60% by weight water b) 3 to 9%by weight 1,2-benzisothiazolin-3-one (BIT); c) 2 to 7% by weight3-iodo-2-propynl butyl carbamate (IPBC), wherein BIT and IPBC arepresent in amounts effective to provide a weight ratio of BIT:IPBC offrom 0.5 to 1.8; d) 5 to 20% by weight methylbenzimidazole-2-ylcarbamate (BCM); e) optionally, 3-(3,4-dichlorophenyl)-1,1-dimethylurea;f) 0.5 to 3% by weight at least two alkoxylated aliphatic mono-alcohols,including a first alkoxylated aliphatic mono-alcohol which is anethoxylated C10-C18 aliphatic alcohol containing an average of about 6to about 15 ethylene oxide units per molecule and a second alkoxylatedaliphatic mono-alcohol which is an alkoxylated C2-C8 aliphatic alcoholcontaining both ethylene oxide and propylene oxide units; g) 0.2 to 1%by weight at least one sulfonate surfactant; h) optionally, up to 1% byweight of at least one defoamer; and i) at least onethickener/suspending agent, in an amount effective to provide thecomposition with a viscosity of at least 300 cps at 25° C.; wherein thepercentages by weight are based on the total weight of a)-i).
 19. Acoating composition which is resistant to microbiological attack in botha wet state and a dry film state, comprising a composition in accordancewith claim 1 and at least one additional coating ingredient.
 20. Amethod of making a coating composition which is resistant tomicrobiological attack in both a wet state and a dry film state,comprising combining one or more coating ingredients with an effectiveamount of the composition of claim 1 to obtain the coating composition.